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Newland’s Law of Octaves

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  • Last Updated : 02 Mar, 2022

A periodic table is a tabular approach of showing elements in such a way that elements with similar qualities are grouped together vertically. Dobereiner’s Triads and Newland’s law of octaves were earlier attempts at element classification. The broad division of elements into metals and non-metals became ineffective when many new elements were found during the 18th and 19th centuries. Several studies were carried out in order to locate and group elements having comparable qualities. It’s worth noting that early techniques of classifying elements, such as Newland’s law of octaves and Dobereiner’s triads, set the groundwork for the contemporary periodic table’s growth.

Dobereiner’s Triads

The atomic mass serves as the basis for this classification. According to this, groups of three elements with comparable properties are formed when elements are stacked in order of increasing atomic masses. The atomic mass of the triad’s middle element is almost equal to the average of the other two elements’ atomic masses. Li (6.9), Na (23), and K are only a few examples (39).

Newland’s Law of Octaves

A British chemist named John Newlands attempted to combine the 62 elements known at the time in 1864. He arranged them in ascending order according to their atomic weights and discovered that the properties of every eighth element were the same. As a result of this discovery, Newland’s law of octaves was born.

The law of octaves states that when the elements are arranged in ascending order of atomic mass, every eighth element has comparable properties. 

Newlands contrasted the components’ proximity to musical octaves, in which every eighth note is comparable to the first. This was the first time an atomic number was assigned to each element. However, this method of classifying elements was met with skepticism in the scientific community.

Examples of Law of Octaves: 

  • Sodium is one of lithium’s eight elements. Potassium, lithium, sodium, and potassium are the chemical properties of the eight sodium elements.
  • Chlorine is the eighth element after fluorine. The chemical properties of fluorine and chlorine are similar.
  • When elements are arranged in increasing atomic mass order, Newland’s law of octaves states that the properties of the eighth element are the same as the first.

Advantages of Newland Law of Octaves

  1. This law establishes a framework for classifying items with comparable features into groups.
  2. The statute gave the government extensive authority to organise all known elements into a tabular format.
  3. The Newlands law of octave was the first to be based on atomic weight, linking element properties to atomic masses.
  4. For the lighter sections, this method performed significantly better. Lithium, sodium, and potassium, for example, were combined.

Limitations of Newland’s Law of Octaves

  1. In Newland’s periodic classification, some elements were grouped together. Nickel and cobalt were both placed in the same slot.
  2. Element qualities that were distinct were grouped together. Metals such as cobalt, nickel, and platinum, for example, were classified with halogens.
  3. Only up to calcium did Newland’s law of octaves hold true. Elements with higher atomic masses had atomic masses that were too large to fit within octaves.
  4. The octave layout was unable to accommodate later discovered components. As a result, new elements could not be discovered using this classification scheme. Elements that were discovered later could not be incorporated into the octave pattern. As a result, this method of classifying elements left no room for the discovery of new elements.

Sample Questions 

Question 1: Why are the Noble Gases Placed in a Separate Group? 

Answer:

Noble gases such as helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are the most inert (non-reactive) of all known elements and are present in very low concentrations in our atmosphere. As a result, in Mendeleev’s periodic table, they are grouped together in a separate group called zero groups.

Question 2: Give a brief history of periodic classification of elements.

Answer:

The periodic table has a history that spans over a century of progress in chemical property understanding. Dmitri Mendeleev published the table in 1869. He based his work on previous discoveries made by scientists such as Antoine-Laurent de Lavoisier and John Newlands.

  1. The triads of Dobereiner
  2. The Law of Octaves of Newland
  3. Periodic Law of Mendeleev

Question 3: What were the drawbacks of Dobereiner’s triads? 

Answer:

The drawbacks of Dobereiner’s triads are:

  • Dobereiner was only able to identify three triads. He couldn’t make triads of all the known elements.
  • All of the known elements could not be arranged in triads.
  • The law did not hold true for elements with extremely low or extremely high masses. Consider F, Cl, and Br.

Question 4: What are the advantages of the Newland Law of Octaves?

Answer:

Advantages of the Newland Law of Octaves are:

  1. This law establishes a framework for classifying items with comparable features into groups.
  2. The statute gave the government extensive authority to organise all known elements into a tabular format.
  3. The Newlands law of octave was the first to be based on atomic weight, linking element properties to atomic masses.
  4. For the lighter sections, this method performed significantly better. Lithium, sodium, and potassium, for example, were combined.

Question 5: What is Mendeleev’s Periodic Table? Which elements were left by him in his periodic table that was discovered later?

Answer:

Dmitri Mendeleev, a Russian chemist, published a periodic table in 1869, just five years after John Newlands proposed his Law of Octaves. Mendeleev also arranged the elements known at the time in order of relative atomic mass, but he also did a few other things that contributed to the success of his table. Mendeleev recognized that the physical and chemical properties of elements were ‘periodically’ related to their atomic mass, and arranged them in his table so that groups of elements with similar properties fell into vertical columns.

Germanium, Scandium, and Gallium are the elements discovered but not included in Mendeleev’s periodic table.

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